Inventive concepts relate to a semiconductor memory device, and more particularly, to a vertical semiconductor memory device.
In order to satisfy excellent performance and low cost of semiconductor devices, there have been efforts to increase the integration degree of the semiconductor devices. In particular, integration degree of a memory device is an important factor in determining a product price. Integration degree of a two-dimensional memory device is mainly determined by an area occupied by a unit memory cell. Hence, the integration degree of the two-dimensional memory device may be significantly affected by a technical level of a fine pattern forming technique.
However, extremely expensive equipment are used for achieving fine patterns. The integration degree of the two-dimensional memory device has been increased but is still limited. Therefore, a semiconductor memory device having a three-dimensional structure has been proposed.